Oldest Known Snake Fossils Push Back Evolutionary Origins

Scientists have discovered what may be the oldest known snake fossils, between 143 and 167 million years old, which could possibly push back the evolutionary origins of these legless reptiles, according to new research.

Until now, the fossils considered to be the oldest remains of snakes were from around 100 million years ago. But these latest fossilized remains of four ancient snake species, found in England, Portugal and the United States, could be as much as nearly 70 million years older.

"The study explores the idea that evolution within the group called 'snakes' is much more complex than previously thought," study leader Michael Caldwell, from the University of Alberta in Canada, said in a statement. "Importantly, there is now a significant knowledge gap to be bridged by future research, as no fossils snakes are known from between 140 to 100 million years ago."

Prior studies have suggested that snake evolution is more complex than previously thought, suggesting that their characteristic long, thin skull structure evolved after the animals became legless and developed their elongated bodies.

However, this new study turns that idea on its head, arguing the complete opposite.

"Based on the new evidence and through comparison to living legless lizards that are not snakes, the paper explores the novel idea that the evolution of the characteristic snake skull and its parts appeared long before snakes lost their legs," Caldwell explained.

Caldwell stumbled upon and identified the first of the four ancient snake species in 2004 at the Natural History Museum in London. Parviraptor estesi, dating back 143 years ago, is the youngest of the specimens this study describes. And although its remains are only fragmentary, yielding little information about the reptile's overall shape, length or body form, researchers can tell that its skull anatomy is similar to that of modern snakes.

According to Caldwell and his colleagues, it's likely that even older snake fossils than these exist.

"If we have got them at 167 million years old, it means that the group had evolved and radiated long before that," he told Live Science.